Microstructure and thermal and functional properties of biodegradable films produced using zein

Crislene Barbosa De Almeida,José Francisco Lopes Filho,Lucimara Aparecida Forato,Elisângela Corradini,Raul Fujihara

doi:10.1590/0104-1428.11516

Abstract

Research is being conducted in an attempt to produce biodegradable packaging to replace plastic products, thereby reducing solid waste disposal. In this work, zein films were produced from vegetable oils (macadamia, olive and buriti) and from pure oleic acid. The surface of zein-based films made using oleic acid has a good lipid distribution. The high content of oleic acid produced a film with the greatest elongation at break (8.08 ± 2.71%) due to the greater homogeneity of the protein matrix. The different oils did not affect the glass transition temperature (Tg). Tg curves of films with fatty acids showed a reduction in mass at between 50 and 120 °C due to water evaporation. At 120 °C the weight loss was 3-5% and above this temperature further weight loss was observed with the highest loss being seen in the film made using pure oleic acid. In conclusion, although biodegradable films were produced using the four different oils, the film made from pure oleic acid has the best characteristics.

Highlights

Around the world, there is great concern about producingPlasticizers are low-molecular-weight organic compounds renewable materials from biomass
Other components were used in the following proportions in respect to 100g of zein: 70g edible vegetable oil purchased at local shops (Vital Atman, La Violeteira and Rio Essências, respectively) or 70g of oleic acid (VETEC, Brazil) and 30g of glycerol (Merck, Brazil) as plasticizers and 5g of Emustab® emulsifier (Duas Rodas Industrial Ltda., Brazil) to facilitate emulsification
The fatty acid composition of oils was investigated at the Instituto de Tecnologia de Alimentos (ITAL), Campinas[26,27,28,29]

Summary

Introduction

There is great concern about producingPlasticizers are low-molecular-weight organic compounds renewable materials from biomass. Due to environmental used to reduce the intermolecular bonding forces, thereby issues and sustainability, biomaterials produced from organic giving high molecular mobility and flexibility to the film[17]. Among the many available raw materials suitable for the production of biodegradable products, starch and proteins are being used to create polymeric matrixes due to their good polymerization properties and because they are totally biodegradable. Both materials, similar to conventional synthetic polymers, are processed with the addition of plasticizers. The greater the amount of glycerol added to produce biopolymer-based films, the lower the stress rupture strength and the Young’s modulus and so the elongation at break is higher. Many formulations include fatty acids, such as oleic, linoleic, stearic and palmitic fatty acids[21]

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Results